Drive arrangement for timekeeping system

ABSTRACT

A drive arrangement for a timekeeping system comprising an electrostatic motor including a rotor having a dielectric surface and a pair of electrodes operatively associated with the rotor for driving the rotor in response to a d-c potential applied across the electrodes. In one embodiment, one of the electrodes is mounted on one of the tines of a tuning fork, and the dielectric rotor surface is serrated for impulsing the tuning fork to vibrate the same while synchronizing the speed of the rotor with the natural frequency of the tuning fork. In another embodiment, both electrodes are mounted on the two tines of a tuning fork, and the serrated rotor is mounted between the electrodes for impulsing both tines of the tuning fork. In a further embodiment, a rotor having a dielectric surface is associated with two pairs of electrodes, each pair being associated with a different circumferential band of the dielectric surface, with one of the electrodes in the first pair connected to one terminal of the d-c voltage source, one electrode in the second pair being connected to the other terminal, and the other two electrodes being interconnected to form a voltage divider across the voltage source. In still another embodiment, the rotor is provided with a discontinuous dielectric surface, and the electrodes are connected to an a-c power source, with a source of ionizing radiation being associated with each electrode for ionizing the gas in the space between each electrode and the dielectric surface to increase the driving force applied to the rotor surface.

ilnited States Patent 1191 Emerson 3,729,925 1451 Mayl,1973

[75] Inventor: Frank W. Emerson, Peterborough,

Ontario, Canada [73] Assignees General Time Corporation, Thomaston,Conn.

'[ii j l iledz Aiig lifi, 1970 [21] Appl. No.: 67,215

Related US. Application Data [62] Division of Ser. No. 830,063, June 3,I969, Pat. No.

Primary Examiner-Richard B. Wilkinson Assistant Examiner-Edith C.Simmons Jackmon Attorney-Pennie, Edmonds, Morton, Taylor and Adams [57]ABSTRACT A drive arrangement for a timekeeping system comprising anelectrostatic motor including a rotor having a dielectric surface and apair of electrodes operatively associated with the rotor for driving therotor in response to a d-c potential applied across the electrodes. Inone embodiment, one of the electrodes is mounted on one of the tines ofa tuning fork, and the dielectric rotor surface is serrated forimpulsing the tuning fork to vibrate the same while synchronizing thespeed of the rotor with the natural frequency of the tuning fork. Inanother embodiment, both electrodes are mounted on the two tines of atuning fork, and the serrated rotor is mounted between the electrodesfor impulsing both tines of the tuning fork. In a further embodiment, arotor having a dielectric surface is associated with two pairs ofelectrodes, each pair being associated with a different circumferentialband of the dielectric surface, with one of the electrodes in the firstpair connected to one terminal of the d-c voltage source, one electrodein the second pair being connected to the other terminal, and the othertwo electrodes being interconnected to form a voltage divider across thevoltage source. In still another embodiment, the rotor is provided witha discontinuous dielectric surface, and the electrodes are connected toan a-c power source, with a source of ionizing radiation beingassociated with each electrode for ionizing the gas in the space betweeneach electrode and the dielectric surface to increase the driving forceapplied to the rotor surface.

2 Claims, 6 Drawing Figures DRIVE ARRANGEMENT FOR TIMEKEEPING SYSTEMThis application is a divisional of my copending application Ser. No.830,063, filed June 3, 1969 now U.S. Pat. No. 3,545,655.

DESCRIPTION OF THE INVENTION The present invention relates generally totimekeeping systems and, more particularly, to an improved drivearrangement for timekeeping systems.

It is a primary object of the present invention to provide an improveddrive arrangement for a timekeeping system which can be operated for anumber of years with a single self-contained power source. A relatedobject of the invention is to provide such a drive arrangement whichserves as a timekeeping standard as well as a source of driving powerfor a time indicating mechanism.

It is another object of the invention to provide an improved drivearrangement of the type described above which can be made with only asingle moving part.

A further object of the invention is to provide an improved drivearrangement of the foregoing type which produce an output suitable forapplication to conventional mechanical timing trains for drivingconventional indicating elements.

Yet another object of the invention is to provide such an improved drivearrangement which can be powered by a high voltage, low current powersource.

A specific object of one particular aspect of the invention is toprovide an improved synchronous drive system of the foregoing type whichproduces rotary motion from an a-c power source.

A still further object of the invention is to provide such an improveddrive arrangement which can be efficiently manufactured at a low cost.

Other objects and advantages of the invention will be apparent from thefollowing detailed description taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a partially schematically side elevation of a drivearrangement embodying the invention, with the power source shown insection;

FIG. 2 is a section taken along line 2-2 in FIG. 1;

FIG. 3 is a partially schematic side elevation of a modified drivearrangement embodying the invention, with the power source shown insection;

FIG. 4 is a partially schematic perspective of another modified drivearrangement embodying the invention, with the power source shown in asectional elevation;

FIG. 5 is a partially schematic top plan view of a further modifieddrive arrangement embodying the invention, with the shrouding plates onthe tips of the electrodes shown in section; and

FIG. 6 is a side elevation of the arrangement shown in FIG. 5, with theshrouding plates on the tips of the electrodes shown in section.

While the invention is susceptible of various modifications andalternative forms, certain specific embodiments thereof have been shownby way of example in the drawings which will be described in detailherein. It should be understood, however, that it is not intended tolimit the invention to the particular forms disclosed but, on thecontrary, the intention is to cover all modifications, equivalents, andalternatives falling within the spirit and scope of the invention.

Turning now to the drawings, there is shown a rotor 10 fixed to a shaft11 which also carries a pinion 12 to be rotated in response to rotationof the rotor 10. As the pinion 12 is rotated, it drives a gear 13connected to a conventional timekeeping and indicating mechanism. Thatis, the pinion l2 and the gear 13 serve to apply the torque generated bythe rotor 10 to a conventional timekeeping and indicating mechanism.

At least the surface of the rotor 10 is made of a dielectric materialoperatively associated with a pair of circumferentially spacedelectrodes, and a beta current nuclear battery is connected to theelectrodes for applying a d-c potential across the electrodes to drivethe rotor. The rotor 10 is molded from a dielectric material, i.e., amaterial which will support an electric charge without conductingcurrent. A pair of tapered electrodes l4 and 15 are mounted close to theouter circumferential surface 10a of the dielectric rotor 10, and areconnected to the positive and negative terminals 17 and 16,respectively, of a source 18 of relatively high dc voltage. When thisvoltage is applied across the two electrodes, a charge having a polarityopposite that of the electrode 15 accumulates on the surface of therotor 10 in the vicinity of the electrode 14. While it is not intendedto limit the present invention to any particular theory, whether it becharge collection or ion wind with respect to the charge carrier, it isbelieved that the relatively high voltage applied to the electrodes 14and 15 causes gas atoms in the vicinity of the electrodes l4 and 15 tobe ionized by the release of electrons therefrom, thereby producing gasions in the space adjacent the electrodes 14 and 15. Since the adjacentsurface 10a of the rotor 10 is a dielectric, the gas ions are collectedand retained on the rotor surface 10a rather than being dissipated.

Electrode 15 has a polarity opposite that of the charges accumulated onthe rotor surface 10a, and electrode 14 has a polarity opposite that ofthe charges accumulated on the rotor surface 10a. Since these chargesexist in an electric field between the electrodes 14 and 15, the chargesare attracted to the electrodes of opposite polarity. Because thecharges cling to the surface of the rotor 10a, rotational motion isimparted to rotor 10. Thus, as the rotor 10 rotates it is believed thatpositive gas ions originating at the electrode 15 cling to rotor surface10a and are transported to the electrode 14, where the charge is lost.It is also believed that as the rotor 10 rotates negative gas ionsoriginating at the electrode 14 cling to the rotor surface 10a and aretransported on the opposite side of the rotor from the positive ions tothe electrode 15, where the charge is lost. This ion wind" theory hastwo possible explanations. First when the gas ions travel in the spacebetween the electrodes 14 and 15 and the rotor surface 10a they give upthe kinetic energy to rotor 10 thereby increasing the torque applied tothe rotor 10. The second theory is that the free charges or gas ions maynot cling tenaciously to the rotor surface 10a and thereby producetorque while sliding over the surface. This ion wind, whether producedin accordance with either of the two theories or a combination of thetwo, contributes only partially to the total torque.

Regardless of whether the particular theories on charge collection orion wind are precisely accurate explanations of the observed phenomenon,it has been repeatedly demonstrated that the dielectric rotor does, infact, rotate in the direction indicated when a relatively high d-cpotential (on the order of 6000 volts, for example) is appliedacross'a'pair of electrodes located close to the rotor surface andcircumferentially spaced therealong. Moreover, it has been found thatsuch a system is capable of generating a torque suffrcient to drive aconventional mechanical timekeeping and indicating system when theelectrodes are connected to currently available d-c voltage sources.Specific working examples of such a drive system will be described inmore detail below. It should be noted that the magnitude of outputtorque generated by any particular system embodying this invention isdependent upon a number of interdependent variables, such as the size ofthe rotor, the electrode spacing both with respect to each other and thedielectric rotor surface, the magnitude of the potential applied acrossthe electrodes, the particular ionizable gas surrounding the electrodesand the dielectric rotor surface, the electrode material the electrodeshapes, the dielectric material, the pressure of the ionizable gas, thetemperature of the electrodes and the surrounding gas, and the like.

The source of the d-c potential applied across the electrodes 14 and 15is a beta current nuclear battery comprising a casing 19 forming avacuum chamber containing an internal emitter and an internal collector21. The surface of the emitter 20 facing the collector 21 is coated witha radioactive material so as to generate a d-c potential across the twoexternal terminals 16 and 17 connected to the collector 21 and theemitter 20, respectively. Constant beta nuclear batteries of the typeillustrated are well known per se, and thus the illustrative source 18will not be described in detail herein. Briefly summarized, theradioactive material on the emitter 20 emits radiation such as betaparticles which are collected on the collector 21, leaving the anodeplate with a positive charge relative to the anode 21. Since the betaparticles expend kinetic energy against the electrostatic field whichexists between the collector and emitter, potential energy on the orderof several thousand volts is developed at the external terminals.Although beta current nuclear batteries of this type have been known perse, the relatively low power available from such sources has tended tolimit the practical application thereof. One of the significantadvantages of the present invention is that the electrostatic motorutilizes the high voltage, low current output from the nuclear batteryto provide an output torque suitable for driving a conventionalmechanical timekeeping and indicating mechanism.

In accordance with the present invention, at least one of the electrodesassociated with the dielectric rotor surface is mounted on one of thetines ofa tuning fork, and the dielectric rotor surface is serrated forimpulsing the tuning fork to vibrate the tines thereof in response torotation of the rotor. This vibratory motion of the tuning fork tines inturn cooperates with the dielectric serrated rotor surface to stabilizethe speed of the rotor at a speed proportional to the frequency of thevibratory motion; since an inherent characteristic of tuning forks is aconstant frequency of vibration, the synchronization of the rotarymotion of the rotor with the vibratory motion of the tuning fork resultsin a substantially constant rotor speed. Thus, in the illustrativeembodiment shown in FIG. 1, the electrode 14 is mounted on one tine 30of a tuning fork 31. To balance the tuning fork, a counterweight 32 ismounted on the other tuning fork tine 33. For the purpose of applyingdriving impulses to the tuning fork 31 in response to rotation of therotor 10, and to synchronize the rotary motion of the rotor 10 with theconstant-frequency vibratory motion of the tuning fork 31, thecircumferential dielectric surface 10a of the rotor 10 is serrated, asshown most clearly in FIG. 1. As the rotor 10 is rotated, the chargecollected on the serrated surface 10a produces a variable attractiveforce on the electrode l4, and thus the tine 30 on which the electrodeis mounted, hereby vibrating the tuning fork at its natural frequency ofvibration.

Although the driving impulses are applied to only one of the tuning forktines in the embodiment of FIGS. l and 2, it will be appreciated bythose familiar with this art that the application of such impulsesresults in vibration of both tines of the tuning fork. Since the tuningfork 31 inherently vibrates at its natural frequency, the electrode 14is repetitively advanced and retracted relative to the serrated surfaceof the rotor 10 at the natural frequency of the tuning fork. Thisvibratory movement of the electrode tends to synchronize the movement ofthe serrated surface of the rotor with the natural frequency of thetuning fork. More particularly, the vibratory motion of the electrode 14on the tuning fork tends to control the rotor speed so that theelectrode reaches its most retracted position when it is directlyaligned with one of the depressed areas 10a in the dielectric rotorsurface and so that the electrode 14 reaches its most advanced positionwhen it is directly aligned with one of the peaks 10b on the dielectricsurface.

If the rotor moves at a speed which is out of synchronism with thevibratory movement of the elec trode 14, the electrode 14 will reach itsmost advanced position when aligned with an inclined portion of thedielectric surface somewhere between a depression 10a and a peak 1012.More specifically, if the rotor accelerates relative to the vibratorymotion of the tuning fork, the electrode 14 will reach its most advancedposition when aligned with one of the forwardly facing inclined surfaces100, so that the attracting force exerted by the electrode 14 on theserrated dielectric surface has a braking effect on the rotor so as torestore the rotor to synchronization with the vibratory movement of thefork. On the other hand, if the rotor decelerates relative to thevibratory motion of the tuning fork, the electrode 14 will reach itsmost advanced position when aligned with one of the rearwardly facinginclined surfaces 10d, so that the attracting force exerted by theelectrode 14 on the serrated dielectric surface has an acceleratingeffect on the rotor, to restore synchronization between the rotarymovement of the rotor and the vibratory movement of the tuning fork.

in accordance with one specific embodiment of the invention, each of thetwo electrodes associated with the dielectric rotor surface is mountedon the inside surface of a different one of the tuning fork tines, andthe rotor is mounted between the tines so that the serrated surface ofthe rotor cooperates with both of the electrodes, thereby impulsing bothof the tines in synchronism with each other. Thus, in the illustrativeembodiment shown in FIG. 3, a relatively wide tuning fork 40 carries thetwo electrodes 14 and 15 on the inside surfaces of the two tines 41 and42, respectively. The electrodes are connected to the d-c potentialsource 18 via the conductive metal of the tine, and a conductor frombattery terminal 16 to electrode 14. Electrode 14 is insulated from thetine 41 by an insulator 45. A rotor 43 is mounted directly between thetwo electrodes 14 and 15 for rotation by the phenomena describedheretofore, with the two tines 41 and 42 being impulsed by thealternating forces exerted on the electrodes by the charge on theserrated surface of a rotor 43. The rotor 43 is similar to the rotordescribed previously in connection with FIGS. 1 and 2, except that it ismade smaller in order to fit between the tines of the tuning fork 40.The theory of operation is also the same as described in connection withFIGS. 1 and 2, except that the second electrode is added and vibrates inthe same manner as electrode 14 through the variable attraction to rotor43. Consequently, if the synchronism between the rotary movement of therotor 43 and the vibratory movement of the tuning fork 40 is disturbed,the electrodes 14 and 15 accelerate the rotor by the repelling forcesexerted on the rearwardly facing inclined surfaces 100, and deceleratethe rotor by the attracting forces exerted on the rearwardly facinginclined surfaces 100. Thus, the electrodes l4, 15 are positioned sothat the electrodes 14 and 15 normally reach their most retractedposition when aligned with depressions 10a, and their most advancedposition when aligned with a peak 10b, when the rotor and the tuningfork are in synchronism with each other.

In accordance with another aspect of the present invention, twodifferent pairs of electrodes are operatively associated with twodifferent circumferential bands of the dielectric rotor surface, withone electrode of the first pair being connected to the positive terminalof the d-c potential source, one of the electrodes of the second pairbeing connected to the negative terminal of the d-c potential source,and the other two electrodes being interconnected. Thus, in theillustrative embodiment of this particular species of the inventionshown in FIG. 4, a rotor 50 forms two circumferential dielectricsurfaces 51 and 52 along the axis thereof. Each of the dielectricsurfaces 51 and 52 extends continuously around the outer surface of therotor 50, in the circumferential direction, with the two surfaces 51 and52 being separated by an annular insulating flange 53. Associated withthe two dielectric surfaces 51 and 52 are two pairs of electrodes 54, 55and 56, 57, respectively. The d-c potential generated by the highvoltage, low current source 18 is applied across the two electrodes 54and 56, and the other two electrodes 55 and 57 are interconnected so asto form a voltage divider connected across the terminals of the source18. Consequently, half of the potential generated by the source 18 isapplied across the first pair of electrodes 54 and 55, associated withthe dielectric surface 51, and the other half of the potential generatedby the source 18 is applied across the second pair of electrodes 57 and56, associated with the second dielectric surface 52. v

The two 'pairs of electrodes 54, 55 and 56, 57 are oriented relative tothe dielectric surfaces 51 and 52 in such a manner that both pairs ofelectrodes drive the rotor 50 in the same direction. This arrangementhas the advantage of providing more efficient utilization of relativelyhigh d-c potentials, such as are generated by beta current nuclearbatteries for example. Thus, if the nuclear battery 18 generates a d-cpotential of 12,000 volts, for example, 6,000 volts may be appliedacross the electrodes 54 and 55 to apply a first driving force to therotor on the dielectric surface 51, and another 6,000 volts may beapplied across the electrodes 57 and 56 to apply a second driving forceto the dielectric surface 52.

In accordance with a further aspect of the invention, there is provideda synchronous drive system for producing rotary motion from an a-c powersource. More particularly, a rotor having a dielectric surface that isdiscontinuous around the circumference of the rotor is disposed in anionizable gas, and a pair of electrodes connected to the a-c powersource are operatively associated with the discontinuous dielectricsurface for driving the rotor in response to the a-c voltage generatedby the source. Since the potentials available from a-c power sources aretypically lower than the potentials available from d-c power sourcessuch as beta current nuclear batteries, the driving force applied to therotor with the discontinuous dielectric surface is increased byproviding sources of ionizing radiation associated with the twoelectrodes for ionizing the air or other gas in the space between eachelectrode and the dielectric rotor surface. Thus, in the illustrativeembodiment illustrated in FIGS. 5 and 6, a rotor 60 includes a centraldisc 61 carrying a plurality of equally spaced, axially extending flangesegments 62 made of a dielectric material. Mounted on diametricallyopposite sides of the rotor 60 are electrodes 63 and 64 connected to aconventional a-c power source 65. During alternate half cycles of thea-c signal from the source 65 a charge of a predetermined polarity iscollected on the dielectric segments 62 as they move successively pastthe tips of the electrodes 63 and 64. During intervening half cycles ofthe a-c signal from the source 65 the spaces between the dielectricsegment 62 are aligned with the tips of the electrodes 63 and 64, sothat charges of a polarity opposite that of the charges accumulated onthe segments 62 are dissipated. Consequently, it can .be seen that thedriving forces applied to the rotor 60 are of a pulsating nature, andare synchronized with the frequency of the ac signal from the source 65,thereby providing a synchronous drive system.

In keeping with the invention, the tips of electrodes 63 and 64 areshrouded with hemispherical plates 66 and 67, respectively, which arelined on their inner surfaces with layers of radioactive material foremitting alpha particles in the spaces between the electrodes and therotor surface. The alpha particles make the gas more conductive byfilling the intervening spaces between the electrodes 66 and 67 withpositive gas ions and electrons. The positive ions and electrons therebyproduced travel to the electrodes of the opposite polarity.Consequently, the rotor 60 is driven at a speed sufficient to drive atimekeeping system, even though the input voltage supplied by the a-cpower source 65 is relatively low.

I claim as my invention:

1. An improved drive arrangement for a timekeeping system comprising thecombination of a rotor having a dielectric surface, first and secondelectrodes operatively associated with a first portion of saiddielectric surface for driving said rotor in a predetermined directionin response to a d-c potential applied across said first and secondelectrodes, third and fourth electrodes operatively associated with asecond portion of said dielectric surface for driving said rotor in saidpredetermined direction in response to a d-c potential applied acrosssaid third and fourth electrodes, a source of d-c potential having apositive terminal connected to said first electrode and a negativeterminal connected to said fourth electrode, said second and thirdelectrodes being electrically connected so that said first and secondelectrodes and said third and

1. An improved drive arrangement for a timekeeping system comprising thecombination of a rotor having a dielectric surface, first and secondelectrodes operatively associated with a first portion of saiddielectric surface for driving said rotor in a predetermined directionin response to a d-c potential applied across said first and secondelectrodes, third and fourth electrodes operatively associated with asecond portion of said dielectric surface for driving said rotor in saidpredetermined direction in response to a d-c potential applied acrosssaid third and fourth electrodes, a source of d-c potential having apositive terminal connected to said first electrode and a negativeterminal connected to said fourth electrode, said second and thirdelectrodes being electrically connected so that said first and secondelectrodes and said third and fourth electrodes form a voltage divideracross said source of d-c potential.
 2. An improved drive arrangement asset forth in claim 1 which includes a constant current nuclear batteryconnected to said electrodes for applying a d-c potential across saidelectrodes to drive said motor.